Contribution of scaffoldins to biomass degradation by C. thermocellum and the effect of scaffoldin-deletions on expression of other genes
Tuesday, April 29, 2014
Exhibit/Poster Hall, lower level (Hilton Clearwater Beach)
Qi Xu1, Kara Podkaminer1, Michael Resch1, Bryon Donohoe1, Daniel Olson2, John O. Baker1, Steven D. Brown3, Dawn M. Klingeman3, Mustafa H. Syed3, Lauren Magnusson1, PinChing Maness1, Stephen Decker1, Lee Lynd2, Yannick Bomble1 and Michael E. Himmel1, (1)Biosciences Center, National Renewable Energy Laboratory, Golden, CO, (2)Thayer School of Engineering, Thayer School of Engineering at Dartmouth College, Hanover, NH, (3)Biosciences Division and BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN
The cellulosome system contributes greatly to the extreme efficiency of C. thermocellum cellulose degradation. In order to further understand the cellulosome working mechanism, we have knocked out C. thermocellum scaffoldin genes to generate a variety of deletion mutants. The knockout most detrimental to enzymatic hydrolysis by the secretome is that of the primary scaffoldin CipA. Deletion of multiple secondary scaffoldins results in secretome activities intermediate between those of the parent strain and the CipA-knockout mutants.  The order of relative secretome activities is the same, whether the cellulosic substrate is microcrystalline cellulose (Avicel) or deacetylated acid-pretreated corn stover (DACS), but the relative magnitudes of the deletion effects are strongly substrate-dependent.  Similar trends are observed in fermentation studies of the abilities of the parent and knockout strains themselves to utilize Avicel and DACS.  Data from transcriptomic and proteomic studies of these strains when grown on both substrates are used to relate the activity and growth effects of the deletions to their effects on the overall expression of lignocellulose-degrading enzymes by C. thermocellum.